1. Field of the Invention
The present invention is generally directed to a powdery mold coating agent supply device.
2. Discussion of the Background
In die casting, mold lubricants play a very important part in prolonging the life of mold and/or improvement in production productivity due to the fact that the mold lubricants prevent an adhesion of molten metal onto an inside surface of the mold, prevent burn-in of the inside surface of the mold, and improve establishment of an easy separation of a die-cast product from the mold. Of the mold lubricants, a water-soluble mold lubricant is widely employed. However, with respect to such an employment of the water-soluble mold lubricant, the following problems or disadvantages have been noted. The mold lubricant remains in the mold and the resultant gas is introduced into the die-cat product, resulting in making the product poor. The mold lubricant is applied on the inner surface of the mold with the mold opened, which causes the mold lubricant to fly in all directions, thereby determining the working environment.
In view of such problems, a recent technology has developed a new powdery mold lubricant whose solvent is free from water and which is capable of being applied onto an inside surface of a mold. For the application of such a powdery mold lubricant, a powdery mold lubricant apply device is provided which is disclosed in Japanese Patent Laid-open Print No. Hei. 11(1999)-128814.
In detail, referring to FIG. 9(a) and FIG. 9(b), there is illustrated the aforementioned powdery mold lubricant application device. The device includes a tank 102 in which an amount of the above-mentioned powdery mold lubricant is stored. The tank 102 is provided at its lower end portion with an outlet 101 with an orifice 104. The outlet 101 of the tank 102 is in fluid communication with an air reverse-flow channel 105 which is defined by a pinch valve 107 and an ejector 110.
A lower wall 103, which constitutes or defines a lower portion of the tank 102, is configured to be elastic. At an outside portion of the lower wall 103, there is provided an air supply port 111 for vibrating the lower wall 103 in a pulsatory fashion. The air supply port 111 is in fluid communication with a pressurized-air source 112 and air under pressure is supplied from the pressurized-air source 112 to the air supply a port 111 in an intermittent fashion or in an on-off fashion such that the number of on-off frequency and/or on-time (off time) duration are arbitrary.
The air reverse-flow channel 105 is provided with an air inlet 113 for air supply to the tank 102 in an upside down fashion. The air inlet 113 is in fluid communication with the pressurized-air source 112. The pinch valve 107 is provided with a pinch rubber 106 and an air supply port 109. The air-supply port 109 is in fluid communication with the pressurized-air source 112 in order that the on and off of air supply from the pressurized-air source 112 causes the pinch valve 107 to open and close, alternately.
The ejector 110 is provided with a discharging hose 115 from which the powdery mold lubricant is discharged to the inside surface of the mold. The ejector 110 is provided with air supply ports 114 and 108 for powdery mold lubricant discharge and air blow, respectively.
In operation, first of all, the pressurized air is applied to the powdery mold lubricant in the tank 102 by way of the air reverse-flow channel 105 for temporally floating the powdery mold lubricant in the tank 102. Next, after such application of the pressurized air from the air reverse-flow channel 105 is terminated, the pressurized air is applied from the air pressure source 112 to the air supply port 111 in on-and-off fashion to bring the lower wall 103 in pulse mode vibration at a fixed interval. At this time, the pressurized air is applied from the air supply port 108 for controlling a supply amount of powdery mold, lubricant in cooperation with the pulse mode vibration of the lower wall 103.
When the pinch valve 107 is closed after termination of the air supply to the air supply port 111, the pressurized air is supplied by way of the air supply port 114 to the ejector 110 for supplying the powdery mold coating agent which is in the form of a mixture with the air to the mold whose cavity is an evacuated state. The sequence of such operations is repeated to apply the powdery mold coating agent onto the inner surface of the mold. However, in the aforementioned or conventional device, while the cooperation of the air supply to the air supply port 108 and the pulse mode vibration of the lower wall 103 measure or determine the amount of the powdery mold coating agent, when an air leakage occurs at the air supply port 108, such air is brought into mixture with the powdery mold coating agent, and the resultant combination or air-mixed powdery mold coating agent is fed into the cavity of the mold. Thus, the advantage or merits in previously evacuation of the cavity of the mold is diluted or lowered, which reduces the adhesive or bonding ability of the powdery mold coating agent onto inner surface at details in the cavity, resulting in that the powdery mold coating agent becomes difficult to adhere to or be apply evenly onto the inner surface in the cavity. Consequently, the releasing function or effect of the powdery mold lubricant fails to be fully realized, which results in a quality problem in die-cast productions.
Thus, a need exists to provide a powdery mold coating agent supply device which is free from the foregoing problems or drawbacks, which is capable of establishing an even application of a powdery molding coating agent onto an inner surface of a mold, and which can permit the mold to die cast a high-quality production.